The present application was filed on Jun. 19, 2000 as international application serial number PCT/SE00/01285 and claims priority of Swedish patent application No. 99002450-7 filed on Jun. 29, 1999.
The present invention relates to nonionic compounds of the polyoxyalkylene type that are low-foaming and can be used as surfactants, especially in cleaning compositions at an alkaline pH. They are obtainable from unsaturated nitriles, that have been epoxidised with e.g. hydrogen peroxide, and alkyl blocked polyalkylene glycols. The nitrile surfactants can be reacted further with e.g. hydrogen peroxide under alkaline conditions to obtain amides. Amide derivatives of this type can also be obtained from unsaturated acids or esters that have been epoxidised and thereafter reacted with alkyl blocked polyalkylene glycols. These acid or ester derivatives are transformed to the corresponding amide derivatives by reaction with ammonia or a primary or secondary amine.
Nonionic surfactants constitute an important group of surface-active compounds that are widely used in numerous applications. However, many of the ethylene oxide adducts containing a hydrophobic chain with 12-22 carbon atoms are too high-foaming to be used in certain applications, such as e.g. machine dish-washing, machine washing of textiles, bottle cleaning and cleaning of hard surfaces.
It has been suggested in EP-A2-0 754 667 to produce new nonionic surfactants, that would generate less foam, by reacting an epoxidised fatty acid ester with a polyglycol ether. These ring-opened products are claimed to be particularly suited to be used as defoamers in a variety of applications. In WO 94/07840 similar products are obtained by reacting epoxidised esters with fatty alcohol polyglycol ethers. These products are claimed to be low-foaming and to have a good biodegradability, and are used as auxiliaries in the removal of water from solid materials.
However, there is a drawback when using the ester polyglycol ether compounds, since the ester group is readily hydrolysed when subjected to highly alkaline conditions. This excludes applications where a high pH is required, since the nonionic product would then be converted to an anionic product.
Nonionic products containing a cyano group, which is a more stable functional group than the ester group, have been described by Wrigley, Smith and Stirton (J. Am. Oil Chem. Soc. 39:80-84 (1962)). These surfactants were obtained by treatment of an unsaturated nitrile with 98% formic acid and 30% hydrogen peroxide to give the hydroxy-formate, followed by mild hydrolysis to yield the dihydroxy compound, which was then ethoxylated using KOH as a catalyst. However, since both the hydroxyl groups of the intermediate product are secondary, the final product will not be very-well defined. Once an ethylene oxide unit has been attached to the secondary hydroxyl group, there will be a primary hydroxyl group present, which will add another ethylene oxide unit much faster than the remaining secondary groups. The end result will be a product where one of the polyoxyethylene chains is much longer than the other, a lot of the polyoxyethylene homologues will probably contain only short chains, and some part of the hydrophobic diol will even be unreacted. Thus, in the above-mentioned article it is stated that ethoxylation of 9,10-dihydroxystearonitrile with 4 moles of ethylene oxide leaves 5.9% of starting diol.
Consequently there is a need for low-foaming products that are more stable than the prior known ester polyglycol ethers and better defined than the ethoxylated diol nitriles. The purpose of the present invention is to provide such products.
It has now been found that these objectives can be met by a new class of low-foaming well-defined compounds, which can easily be prepared from starting materials that are easy to handle and that can be obtained by standard procedures, by reacting an epoxidised nitrile with an alkyl blocked polyalkylene glycol. Since the compounds that are obtained are low-foaming, they are suitable to use e.g. in cleaning compositions for applications where low foam is required, such as vehicle cleaning, bottle cleaning and machine-washing. To obtain products with even better toxicological and environmental profiles that still are relatively stable, the nitrile group can be converted to an amide group by treatment with e.g. alkaline hydrogen peroxide. An amide derivative according to the invention could also be produced by the reaction between an acid or ester derivative of the type described in EP-A2-0 754 667 and ammonia or a primary or secondary amine.
The nonionic compounds according to the present invention are characterised by the general formula RY (I), where R is a substituted aliphatic group containing 1-3 structure elements with the formula 
where the carbon atoms shown in the structure element are part of the aliphatic carbon skeleton of group R, which. contains 8-24 carbon atoms, preferably 12-22 carbon atoms, and Y is a nitrile or an amide group; R3 is an alkyl group with 1-4 carbon atoms; AO is an alkyleneoxy group containing 2-4 carbon atoms and n is a number between 1 and 30, preferably 3-20. The number of structure elements contained in the chain is preferably 1-2.
Suitable examples of the above-mentioned compounds are those having the formulae 
where R1 is an aliphatic group, R2 is an aliphatic radical, the sum of carbon atoms contained in R1 and R2 is between 9 and 19 and R3, AO, n and Y have the same meaning as above.
Suitable amide groups are those having the formula 
where R4 and R5 independently are H, an alkyl group with 1-6 carbon atoms, preferably 1-4 carbon atoms, or (AO)m where AO is an alkyleneoxy group containing 2-3 carbon atoms, preferably 2, and m is 1-20, preferably 1-2. Most preferably at least one of R4 and R5 is H.
The nonionic compounds according to the invention may be produced by
a) reacting an epoxidised nitrile containing 1-3 epoxy groups and a total of 8 to 24 carbon atoms, preferably 12-22 carbon atoms, with an alkyl blocked polyalkylene glycol having the formula R3O(AO)nH, where R3, AO and n has the same meaning as in formula II, in the presence of a catalyst, and optionally subjecting the product obtained to alkaline hydrogen peroxide or
b) reacting ammonia or a primary or secondary amine with an acid or an ester containing 1-3 structure elements according to formula II in the aliphatic skeleton. The alkyleneoxy groups could be distributed randomly or in blocks or a mixture thereof. Normally at least 50% of the alkyleneoxy groups are ethyleneoxy groups. Alkyl blocked polyethylene glycols are the reactants most often used. Suitable examples of alkyl blocked polyalkylene glycols are CH3(CH2CH(CH3)O)2(CH2CH2O)10R and CH3(CH2CH2O)14H.
When the reaction between a monoepoxidised nitrile and the alkyl blocked polyalkylene glycol takes place, there is an equal chance for attack by the glycol on either of the two carbons in the epoxy ring. Consequently two regioisomers are formed in about the same amount, as is shown by formula IIIa and IIIb.
The epoxidised nitrites could be derived from unsaturated nitriles e.g. by using the Venturello method described in GB-A-2055821, where hydrogen peroxide is used as the source of active oxygen, or by the use of peracids. The unsaturated nitriles could contain more than one double bond, and the epoxidation of such polyunsaturated nitriles can consequently give rise to products containing more than one epoxy group. Accordingly, the nonionic compounds derived from such polyepoxidised nitrites could contain several polyoxyethylene chains distributed along the aliphatic skeleton. Naturally occurring fatty acids, which are the starting material for the nitrites, are normally mixtures between acids with different amounts of double bonds, and consequently the resulting end products will also be mixtures of compounds containing different numbers of polyoxyethylene chains.
The unsaturated nitriles are intermediates in the process for the manufacturing of fatty amines, and they are thus readily available in large quantities. Oleonitrile is a suitable example of an unsaturated nitrile, but also other nitrites derived from unsaturated acids would be possible to use. Examples of such acids are tall oil acid, linoleic acid, erucic acid and fish-oil acids, as well as unsaturated synthetic acids.
The reaction between the epoxynitriles and the alkyl blocked polyalkylene glycols could be catalysed both by acids, such as Lewis acids e.g. BF3, and by alkali, such as alkoxides.
The conversion of the nitrile group to an amide group by the treatment with alkaline peroxide is described e.g. in Organic Synthesis Collective Vol. II p. 586.
The nonionic amide compounds according to the invention could also be obtained by a standard procedure via the suitable acid or ester derivatives by reaction with ammonia or an amine. Suitable examples of amines are primary or secondary alkylamines, ethanolamine and diethanolamine.
The following examples are illustrative of the invention and are not to be construed as limiting thereof.